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https://issues.apache.org/jira/browse/CALCITE-2973?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16821654#comment-16821654
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Haisheng Yuan edited comment on CALCITE-2973 at 4/19/19 4:56 AM:
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{quote}
For the record, here is a non-equi join where you can use a hash join plus a
per-row condition, where the 'equi' part of the condition is fairly selective
and therefore hash join makes sense. It has to be done as a per-row condition,
rather than a filter after the join, because of the left outer.
{quote}
[~julianhyde] We have different definition of equi join. The Oracle's
definition of equi join makes more sense:
https://docs.oracle.com/cd/E11882_01/server.112/e41084/queries006.htm#SQLRF52350
Update:
My mistake, looks like it still refers to join that has equality condition
*only*.
was (Author: hyuan):
{quote}
For the record, here is a non-equi join where you can use a hash join plus a
per-row condition, where the 'equi' part of the condition is fairly selective
and therefore hash join makes sense. It has to be done as a per-row condition,
rather than a filter after the join, because of the left outer.
{quote}
[~julianhyde] We have different definition of equi join. The Oracle's
definition of equi join makes more sense:
https://docs.oracle.com/cd/E11882_01/server.112/e41084/queries006.htm#SQLRF52350
> Allow theta joins that have equi conditions to be executed using a hash join
> algorithm
> --------------------------------------------------------------------------------------
>
> Key: CALCITE-2973
> URL: https://issues.apache.org/jira/browse/CALCITE-2973
> Project: Calcite
> Issue Type: New Feature
> Components: core
> Affects Versions: 1.19.0
> Reporter: Lai Zhou
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Now the EnumerableMergeJoinRule only supports an inner and equi join.
> If users make a theta-join query for a large dataset (such as 10000*10000),
> the nested-loop join process will take dozens of time than the sort-merge
> join process .
> So if we can apply merge-join or hash-join rule for a theta join, it will
> improve the performance greatly.
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